To surely and accurately enable the supplying of molten metal in a short time and to enable the discharge of the whole molten metal in a ladle for supplying molten metal after completing casting work by discharging the molten metal in the ladle for supplying molten metal after inserting the lower part of the ladle for supplying molten metal into a tilted injection sleeve.

The ladle 100 for supplying molten metal is shifted to a holding furnace while holding the tilted attitude at the upward side of a molten metal hole till forming as the almost same angle as the inclining angle of the injection sleeve and the lower part of an introducing tube 112 is dipped into molten metal surface in the holding furnace. The dipped depth is made so that the lower end of the introducing tube dips into about 5-20 mm from the molten metal surface and the bottom surface plate 110a is not brought into contact with the molten metal surface. Therefore, the drop and mixing of the stuck material on the injection sleeve can be prevented and the cleanliness of molten metal can be held to high degree. Thereafter, while measuring the weight with a weight detecting means 210, an evacuating device 130 is driven till reaching a prescribed weight to suck the gas in the ladle 100 for supplying molten metal.